US TV network CBS has apologised after its Emmy-winning reality series The Amazing Race angered veterans with an episode featuring Vietnamese communist propaganda.

The show's host, Phil Keoghan, apologised before the start of Sunday's show for the episode that was screened in the US on March 17 in which participants in Hanoi were required to memorise a pro-communist song and use a downed US B-52 bomber aircraft in the city as a prop.

"We want to apologise to veterans - particularly those who served in Vietnam - as well as to their families and any viewers who were offended by the broadcast," said Keoghan, reading from a statement.

The Amazing Race is a competition in which teams travel around the world to complete challenges and vie for a US$1 million cash prize.

About 58,000 US troops were killed during the Vietnam War (1964-1975) against communist North Vietnam. More than 7 million US Vietnam veterans are still alive.

James E. Koutz, a Vietnam veteran and head of the American Legion veterans group who demanded an apology last week from CBS, said on Monday he believed the network's statement was "sincere and heartfelt."

"America is a forgiving country," Koutz said in a statement. "When you make a mistake, you own up to it."

US Senator John McCain of Arizona, a former prisoner of war in North Vietnam and one of the country's most prominent Vietnam veterans, said CBS "did the right thing by apologising."